1. Field of the Invention
The present invention relates to an airbag inflatable with inflation gas.
2. Description of Related Art
JP8-104194 discloses an airbag that includes on an area exposed to heat and pressure of inflation gas and provided with a plurality of mounting holes used to mount the airbag to a predetermined location a laminated area where more than one base cloths for forming the bag overlap for enhancing tensile strength.
The laminated area is provided for reinforcement by bonding one or more sheets of small reinforcing cloth to a body cloth that forms a bag-shaped circumferential wall. Those base cloths are made of fabric woven by multifilament yarns of synthetic fiber such as polyamide, polyester, and the base cloths are bonded together by an adhesive so manufacturers can manufacture airbags easily.
The bonding is conducted either by preparing base cloths having an adhesive layer on one surface, placing two of the base cloths so their adhesive layers butt each other and heating the base cloths under pressure by heat press or the like so the adhesive layers weld together to join the cloths together, or by applying an adhesive between two of the base cloths and bonding the cloths together by heat press or the like.
JP10-129380 discloses an airbag that is formed by bonding outer peripheral edges of base cloths by an adhesive.
However, the latter method that applies an adhesive between two base cloths and bonds the cloths together not only tends to increase an amount of the adhesive used but also takes a painful process of applying the adhesive to every airbag right before the bonding work. It further requires such a process as resolidification, and therefore is not efficient. Accordingly, the former method, i.e. the method of bonding two base cloths preliminarily provided with adhesive layers by heat press or the like, is preferred in the light of reducing the amount of adhesive and process improvement.
However, in such an instance of attaching more than one reinforcing cloths to the body cloth, i.e. in such an instance of overlapping three or more sheets of base cloths on an area to be reinforced, the above method of using base cloths that are preliminarily provided on one surface with an adhesive layer does not work in positioning a third and subsequent cloths. Specifically, it is difficult to bond three or more base cloths together while securing a tensile strength and good handleability and avoiding a slippage of the cloths to a direction orthogonal to a layering (laminating) direction of the cloths. Slippage of two or more sheets of reinforcing cloths in a direction orthogonal to the layering direction will make it difficult to insert mounting means into mounting holes and thus reducing work efficiency.